Yellow Star Seedless

ABSTRACT

A new and distinct variety of seedless lemon tree named ‘Yellow Star Seedless’ characterized by being a triploid, and having early bearing in August through to about January in the citrus areas of Sicily, Italy and Riverside, Calif. The tree has high yields and bears from year three onwards. The trees are highly tolerant to the Mal secco disease. The variety is further characterized by being genetically seedless. The fruit is well sized and has acceptable rind thickness, acid-sugar ratios and color. The skin has a smooth texture and the fruit stores well. The fruit has an average juice content of 30-40% at harvest. The fruit shape is typically ovoid.

This application claims the benefit of European Union Community PlantVariety Office application Designation C-3869 (LEMOX), File Number2004/0073 dated Jan. 22, 2004 a copy of which (with translation) isattached hereto and incorporated herein by this reference.

Citrus limon.

Variety denomination: ‘Yellow Star Seedless’.

BACKGROUND OF THE NEW VARIETY

The present invention refers to a new variety of triploid lemon whichwill hereinafter be denominated as the ‘Yellow Star Seedless’ lemontree. The ‘Yellow Star Seedless’ tree produces commercially seedlesslemon fruit, bearing in late August through to March in the citrus areasof Sicily, Italy. The ‘Yellow Star Seedless’ plant is a triploid—havingthree sets of chromosomes. The trees bear from year three, and haveconsistent year-to-year bearing habits. The fruit has acceptable rindthickness, acid-sugar ratios and color, and has an average juice contentof 30-40% at harvest.

In the development of new commercial fruit varieties, specificcharacteristics provide a premium on those fruit varieties that matureearly or late in the growing season. For a new fruit variety to be acommercial success, the fruit must be of good size, good color, and alsohave good holding/storage. Advantageous harvest times and shippingcharacteristics are also important, as is the date the fruit matures.This new invention meets all of the aforementioned criteria andtherefore would be of commercial appeal to the consumer.

The ‘Yellow Star Seedless’ variety is a triploid sexual hybrid.Polyploidy in citrus is well known (See pp. 191-193 of Speigel-Roy &Goldschmidt, 1996.) Citrus and related genera are typically diploidicand have two sets of 9 chromosomes (2n=18). Triploids, tetraploid andhexaploids exist naturally but occur in low percentages in thepopulation. Citrus triploids are cytologically recognizable by thepresence of an additional set of Chromosomes. In some cases, triploidsare also morphologically recognizable.

ORIGIN AND ASEXUAL REPRODUCTION OF THE NEW VARIETY

The invention (variety) comprises a new and distinct variety of aseedless lemon plant named ‘Yellow Star Seedless’ discovered by theinventors in Azienda S Gregorio (RC), Sicily, Italy in 1999. The newinvention is a triploid (3n=27 chromosomes) selection from sexualcrosses made between a tetraploid (pollen) male parent (‘Doppio Lentini’Lemon) and a diploid (seed bearing) female parent (C.limon (L.) Burm.femminello×‘Pera del Commendatore’) and called ‘Yellow Star Seedless.’The new invention was subsequently asexually reproduced by the inventorsin 2000 by bud grafting on to ‘Sour Orange’ root stock. The resultingtrees were experimentally evaluated. The resulting tree growth wasstrong with no bud union abnormalities being noted on the ‘Sour Orange’rootstock. An additional 10 trees were asexually reproduced by theinventors in 2003 by bud grafting on to ‘Sour Orange’ root stock andgrown in Riverside, Calif. The inventors carefully compared all of theasexually reproduced trees with the originally discovered tree includingthe fruit and found, thus far, that they are identical in all respects.The instant tree reproduces true to type in successive generations ofsuch asexual reproductions. The trees under evaluation are free from allknown viruses and viroids including; Tristeza, Exocortis, Xyloporosisand Psorosis.

SUMMARY OF THE NEW VARIETY

The ‘Yellow Star Seedless’ is particularly characterized by being atriploid, genetically (and hence commercially) seedless, good fruitsize, precocious with stable year-to-year high yields, and an earlybearing variety (August/September) in Northern Hemisphere citrus bearingregions. The trees exhibit high levels of tolerance to the malady knownas Mal secco, a fungal disease of serious importance in theMediterranean citrus regions caused by a fungus called Phomatracheiphila.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a color photograph showing perspective views of severalspecimens of typical whole fruit, and one transversely cut fruit of thepresent invention harvested in September 2002.

FIG. 2 is a color photograph showing a typical branch from a one yearold tree, showing the typical leaf arrangement and minimal thorns of thepresent invention.

FIG. 2 a is a color photograph of a juvenile branch showing thorns andflower buds.

FIG. 3 is a color photograph showing a typical top view of a flower ofthe present invention.

FIG. 4 is a color photograph showing a side sectional view of a typicalcut section of the flower of the present invention.

FIG. 5 is a color photograph of the typical fruit arrangement on abranch.

FIG. 6 is a color photograph of a 4 year old bearing tree.

DETAILED DESCRIPTION

Referring more specifically to the horticultural details of the new anddistinct variety of triploid lemon, the following descriptions have beenobserved on a 4^(th) year tree under the ecological conditionsprevailing at the origin orchard which is located in Sicily, Italy aswell as in Riverside, Calif. Color references are to the Dictionary ofColor by Maerz and Paul, First Edition published in 1930. Common colorsare also employed.

TREE

-   Size: Medium, for 4^(th) year tree.    -   -   Height.—10 feet.        -   Width.—8 feet at drip line.-   Shape: Upright, growth habit when grown on ‘Sour Orange’ rootstock.-   Growth: Dense; vigorous branches tend to grow out, upward beyond    trees' general periphery; abundant axillary and accessory bud    development.-   Vigor: Strong.-   Productivity: Very good for 4^(th) year tree with regular bearing;    fruit produced predominantly inside the canopy resulting in less    fruit scaring.

TRUNK

-   Immediately above the rootstock interface on ‘Sour Orange’:-   Size: Circumference of 12-16 inches, 18 inches above ground.-   Surface texture: Smooth.-   Color: 4 year old tree, Andover green (23-E-2).-   Lenticels: Many.

BRANCHES

-   Size: Scaffold (structural) branches, circumference of 10-12 inches;    Secondary branches (on which fruit bearing branches are borne)    circmference of 4-6 inches.-   Angle of branches extending from main trunk: Average between about    30° and about 50°.-   Color of branches over 2 years old: Andover green (23-E-2).-   Color of branches less than 2 years old: Brunswick green, LT^(P)    (22-L-10).-   Thorns: Reduced as tree matures (See FIG. 2). In juvenile branches    thorns may be present, with the following dimensions:    -   -   Width at base.—2-3 mm (0.1-0.12 in.).        -   Length.—10-15 mm (0.4-0.6 in).        -   Average width at base.—2.5 mm(0.1 in); average length: 12 mm            (0.5 in). (See FIG. 2 a).

LEAVES

The leaves are alternate, unifoliate with distinct articulation betweenthe petiole and leaf blade. They exhibit a slight curvate morphologywith undulation, and are without basal wings.

-   Size: Medium.    -   -   Length.—75-110 mm (3-4.4 in.).        -   Width.—60-70 mm (2.4-2.8 in.).-   Texture: Predominantly smooth to slightly pebbled, depressions in    the adaxial surface corresponding to vein channels. Abaxial surface    has raised leaf veins.-   Shape: Elliptically oval to oblong. Approximately transversely and    longitudinal symmetrical.-   Margin: Smooth serrations at edge.-   Apex: Mild crenation to pointed at the apex (mildly acute).-   Base: Not elongated.-   Edges: Distinctly smoother towards the basal leaf end.-   Marginal oil cells: Many 6-10 per linear cm; oil cells are ovoid and    smooth.-   Color: Mature leaves glossy.    -   -   Upper surface.—Chrome Green LT^(P) (22-L-12).        -   Lower surface.—Light Green (20-K-8).-   Petioles: No wings (characteristic of true lemon).    -   -   Length.—Less than 8-12 mm (0.28-0.48 in.).        -   Diameter.—Less than 3 mm (0.12 in.).        -   Color.—Apple green (19-J-6).-   Venation: Distinct, pinnately reticulated.-   Midvein: Width at base, 1-2 mm (0.04-0.08 in.); Width at apex, 0.3    mm-0.4 mm (0.012-0.016 in.).    -   -   Color.—Chrome Green LT^(P) (22-L-12).

FLOWERS

The flowers are large and complete. Flower buds have pink anthocyanincoloration during early development, but lose the most of theirpigmentation by anthesis. Flowers are borne in single or multipleclusters and have an average number of stamens (about 20-30) withcomplete style development. Anther color is pale yellow to yellow.Pollen fertility is very low to sterile as indicated by the observationthat less than <0.01% of the pollen grains stained with acetocarmine.The flowers have a sweet pleasing citrus fragrance.

-   Flower buds:    -   -   Shape.—10 days prior to anthesis, slightly ovoid, 10 mm (0.4            in.) diameter 1-2 days prior to flowering, elongated cone,            10-12 mm (0.4-0.48 in.) diameter, length — 20-25 mm (0.8-1            in.).-   Calyx: 4-5 sepals, fused forming a cup-like calyx.    -   -   Exterior surface color.—Calliste green (19-L-6). Lobe tips            are blunt but with apiculate tips.-   Date of normal first bloom:    -   -   Sicily, Italy.—First bloom: about March 15^(th); end bloom            about April 15^(th).        -   Riverside, Calif.—First bloom about April 1^(st), end bloom            about April 20^(th).-   Flowers: Medium — in clusters of three to five.    -   -   Diameter when fully opened.—25-40 mm (1-1.6 in.).        -   Bloom.—e.g. quantity — abundant (typical of a lemon)            non-alternate bearing.-   Petals: 4-5, acute tips.    -   -   Size.—Medium to large (compared to other citrus species).            Length: 15-20 mm (0.6-0.8 in.). Width: 5-8 mm (0.2-0.32            in.).        -   Form.—Narrow, linear, slightly oblong.        -   Color.—Adaxial surface — white (1-A-1). Abaxial surface —            White to slightly pink (2-B-1).        -   Claws.—None.-   Petal margins: Smooth, pointed at tips (acute).-   Pedicel: 4-6 mm (0.16-0.24 in.) average.    -   -   Color.—Sea green (19-K-6).-   Sepals: Color: Glass green (18-F-3).-   Stamen: Number: 20-30, with complete style development. Length 10-15    mm.    -   -   Filament.—White (10-A-1).        -   Anthers.—2-4 mm (0.08-0.16 in.) length; 1-2 mm (0.04-0.08            in.) width.        -   Color.—Aureolin^(P) (10-L-2).-   Pistil:    -   -   Stigma.—Ovoid shape, 3-4 mm (0.12-0.16 in.) diameter; Color:            Pineapple (11-J-2).        -   Style.—8-10 mm (0.32-0.4 in.) length; 2-3 mm (0.08-0.12 in.)            wide; Color: Sea foam Y (17-C-2).        -   Ovary.—6-8 mm (0.24-0.32 in.) diameter; ovoid shape; Color:            Imperial jade (21-L-12).

FRUIT

On grafted trees the first fruit production occurred after two seasons.Internal characteristics: The fruit is commercially seedless in itsnormal cropping cycle. There is no persistence of the style on thefruit.

-   Internal characteristics:-   Flesh color: Near rind, yellow (18-I-1); Remainder, yellow (18-I-1).-   Interior segments: Average of 8 to 10 in number.-   Interior segment membranes—Thin.-   Pulp vesicles: Medium, 6-8 mm (0.24-0.32 in.) length; 2 mm (0.08    in.) diameter, color: yellow (18-I-1).-   The septa: Dorsal slightly convex contoured character.-   Juice: Abundant in mature fruit, evenly distributed in sections,    typical lemon flavor: rich, with high acid and low sugar, well    blended. (pH of 3-3.7). The fruit center is complete without    separation. Rind oil cells are medium to large, and occur at a    density of approximately 150-200 per cm².-   Oil: 0.6-0.65% (approx. 625 g oil/100 kg fruit).-   Glandular layer 2-3 mm (0.08-0.12 in.).-   Mesocarp (albedo) 5-8 mm (0.2-0.32 in.).-   Axis: 5-6 mm (0.2-0.24 in.) diameter.-   Fruit weight: Average of 140 g-160 g (mean of 100 fruit per tree and    5 trees).-   Date of maturity: Sicily, Italy: about August 25^(th). Riverside    Calif. About September 5^(th).-   External characteristics:-   Size: Medium.    -   -   Length.—60-70 mm (2.36-2.76 in.).        -   Width.—50-60 mm (1.97-2.36 in.).-   Form: Ovoid.    -   -   Fruit surface.—Smooth.-   Basal (stem end) even to slightly raised.-   Base: Diameter 12-14 mm (0.48-0.56 in.).-   Stem: Length 10-12 mm (0.4-0.48 in.).-   Calyx: diameter 8-12 mm (0.32-0.5 in.).-   Apex: Slightly raised, slightly nippled.-   Areole: Absent.-   Stylar scar: Slight, diameter 1-2 mm (0.04-0.08 in.).-   Rind: Surface — smooth.    -   -   Thickness.—Average 4-8 mm (0.16-0.32 in.).        -   Color.—Shamrock (19-L-12) at first harvest (August)            developing to a deep yellow (17-L-1) by the end of November.

Internal fruit quality acceptability occurs approximately one monthprior to color change.

The above description of this new variety of lemon is based on thegrowing conditions prevalent in the Sicily, Italy and in Riverside,Calif.; variations of the usual magnitude, such as differences inmaturity date and production, may be due to cultural practices includingirrigation, fertilization, pruning, fruit thinning and primary climatechanges as well as soil conditions.

-   Use: fresh market/juice/oil extraction.-   Keeping quality: Excellent (stores for 6 month in controlled    atmosphere).-   First harvest date: Around August 25^(th) in Sicily, Italy. Around    September 5^(th) in Riverside, Southern Calif.

Post harvest disorders are similar to existing lemon varieties. In postharvest storage trials under standard controlled atmosphere conditions,the ‘Yellow Star Seedless’ could be economically stored, with minimalfruit loss for at least 6 months.

Table 1 below compares the fruit skin color, seeds and pollen fertilitybetween fruit harvested from the ‘Yellow Star Seedless’ as compared to‘Siracusano’ Lemon on Sep. 14, 2002. Table 2 below compares the fruit onOct. 19, 2002:

TABLE 1 Fruit skin color Seeds/fruit* Pollen Tree (Sep. 14, 2002) (Sep.14, 2002) fertility** ‘Siracusano’ Lemon Shamrock Gr 5-7 85% (19-L-12)Yellow Star Seedless Spring Gr 0 <0.01% (18-J-7) *500 fruit assessed pertree, 5 trees **Estimated by acetocarmine staining during flowering inApril

TABLE 2 Fruit skin color Seeds/fruit* Pollen Tree (Oct. 19, 2002) (Oct.19, 2002) fertility** ‘Siracusano’ Lemon Yellow 7-9 85% Yellow StarSeedless Endive 0 <0.01% (17-L-3) *500 fruit assessed per tree, 5 trees**Estimated by acetocarmine staining during flowering in April

Table 3 details some preliminary yield data for grafted trees. Table 4compares fruit juice and acid content for the ‘Yellow Star Seedless’lemon as compared to ‘Siracusano’ lemons for the 2002-2003 season.Measurements in each case were carried out on 10 fruit per tree and a 5tree sample giving a total of a 50 fruit sample. Table 5 illustrates atypical picking pattern from the Yellow Star Seedless lemon variety.

TABLE 3 Typical Yield Year Yield Average Fruit Size Yr 1  0 n/a Yr 2  35kg 140 g Yr 3  75 kg 154 g Yr 4 140 kg 162 g

TABLE 4 Fruit Acid ‘Yellow Star Seedless’ ‘Siracusano’ Lemon Acid TSSJuice Acid TSS Juice Date (meq/100 g) (%) % (meq/100 g) (%) % August30^(th) 110 9.1 31 95 9.8 25 September 30^(th) 117 8.3 36 104 8.7 30October 30^(th) 114 7 38.5 111 7.8 31 November 30^(th) 111 6.5 41.5 1097.1 35

TABLE 5 Typical Picking Pattern of the ‘Yellow Star Seedless’ Lemon inSicily, Italy First Pick: 15% of total End August Second Pick 30-40% oftotal End September Third Pick 30% of total Early November Fourth Pick20% of total January

1. A new and distinct early harvesting variety of seedless lemon tree asdescribed and illustrated called ‘Yellow Star Seedless’ that ischaracterized as a triploid having early fruit production from about theend of August through to about January in the citrus areas of Sicily,Italy and Riverside, Calif., the trees coming into bearing by year 3,consistently bearing each year thereafter, and having high tolerance toMal secco disease, the seedless fruit having typically ovoid shape, anaverage juice content of about 30% to about 40% at harvest, with smoothskin texture, and having acceptable rind thickness, acid-sugar ratiosand color.